Chemistry Class 12 NCERT Solutions: Chapter 13 Amines Part 12 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Q: 11. Complete the following reactions:

(i)

(ii)

(iii)

(iv)

(v)

(vi)

(vii)

Answer:

(ii)

(iii)

(iv)

(v)

Structure of Aniline and 2,4, 6-Tribromoaniline

(vi)

(vii)

Q: 12. Why cannot aromatic primary amines be prepared by Gabriel phthalimide synthesis?

Answer:

Gabriel phthalimide synthesis is used for the preparation of aliphatic primary amines. It involves nucleophilic substitution of alkyl halides by the anion formed by the phthalimide.

Structure of Gabriel Phthalimide Synthesis

But aryl halides do not undergo nucleophilic substitution with the anion formed by the phthalimide.

Structure of Gabriel Phthalimide Synthesis

Hence, aromatic primary amines cannot be prepared by this process.

Q: 13. Write the reactions of (i) aromatic and (ii) aliphatic primary amines with nitrous acid.

Answer:

(i) Aromatic amines react with nitrous acid (prepared in situ from and a mineral acid such as ) at to form stable aromatic diazonium salts i.e.. , and .

Aromatic Amines React with Nitrous Acid

(ii) Aliphatic primary amines react with nitrous acid (prepared in situ from and a mineral acid such as ) to form unstable aliphatic diazonium salts, which further produce alcohol and with the evolution of gas.

Aliphatic Primary Amines React with Nitrous Acid

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